Pipe or tube bending machine



Patented Aug. 1, 1939 PIPE R TUBE BENDING MACHINE John Henry Hawes,London, England Application September 8, 1936, Serial No. 99,821

In Great Britain May 12, 1936 8 Claims. (Cl. 153-45) the known art inthat the shield does not have tobe readjusted-for each bending operationof This invention relates to tube or pipe bending machines of the kindin which the tube is bent round a grooved radius wheel or former bymeans of a radial arm or lever which is swung round the former, the armacting on the tube through a grooved shield bearing on the tube roundthe outside of the bend, and the invention relates more particularly toformers for use in such machines.

In the constructions of such machines as hitherto made, the radius wheelor former has been constructed of cast metal or made of solidconstruction so that when tubes of slightly different external diametershave to be bent a differently grooved former to fit the differentexternal diameters of tubes has been required, since the grooved face ofthe former can only be 'given such cross-sectional curvature as tosupport one particular external diameter of tube and if tubes of smallerdiameter than those intended to be bent in the former are used the wallsof the tube are not adequately supported and distortion or crinkling ofthe tube results, while, of course, tubes of slightly larger diameterthan those for which the former is intended cannot be bent withoutdistorting or flattening the tube to enable it to enter the groove inthe former.

The disadvantage of, having a rigid former is particularly apparentinthe plumbingindustry, where tubes are classified according to theirinternal diameter or bore, butmay be'of different gauge materialaccording to the pressure. they are to withstand or the strengthrequired, resulting in the use of tubes of the same bore but havingdifferent thicknesses of wall and consequently slightly differentexternal diameters.

The cast or solid former is also heavy and this is important when thebending machine is required to be portable.

Also, with the constructions now generally in use and referring moreparticularly to thoseshown in my prior U. S. Patents Nos. 1,505,887 and1,530,261 only a short straight shield can. be used between the tubeandthe radial lever by which the bending force is applied; so that when thetube has to be bent through the major portion of a circle the shield hasto be moved round: in steps as the tube is bent. In the presentconstruction the shield is mounted upon a slidable support which in turnis carried by the lever, whereby the shield moves with the lever as thesame is operated, and thereby the shield contacts with the tubethroughout each bending operation of the lever. In this respect thepres- 55} cut inventiondiffers from my prior patents, and

the tube.

If an attempt is made to avoid this repeated re-positioning of theshield by using a longer shield it is found that, although the bendingforce may be suitable at the commencement of the bending operation, bythe time the radial arm has been moved so that the other end of theshield is between the tube and the radial arm the force applied to thetube is changed to such an extent that distortion of the tube results.The object of the present invention is to avoid these disadvantages andto provide a former which can be used for slightly different externaldiameters of tube, and a further object is to provide amachine whichenables a considerable bend to be produced without readjustment of theshield between the bending arm and the former. According to theinvention a former for use in a-bending machine is bent up or pressedout from sheet metal, and has across-section consisting of asemi-circular web having two side wings which preferably project to thediameter of the largest tube which can be fitted into the former so.that this tube is completely within the side wings so that theseprojecting portions of the side wings can receive between them the edgesof the shield used between the tube and the bending arm.

The invention also includes a construction of a bending. machineincorporating a sheet metal former and inv the machine according to theinvention the shield is permanently carried on the bending arm and ismade of a comparatively short length and has its rear or trailing end(that is, the back end as the bending arm is swung round the former)made to fit between the wings of the radius wheel or former, while theleading end projects out from the aforesaid wings and is positioned sothat it is spaced slightly from the tube and thus avoids scoring thelatter. The concave face of the shieldis not made of exact circularcross-section but. is made very slightly oval in section so that theshield does not contact with the wall of the tube being bent over thewhole of its face but only supports the tube at points other than'theextreme outermost circumference of the bend made in the tube by themachine.

former, a complete practically surroundingthe tube.

circular support invention and incorporating a sheet metal former isillustrated in the accompanying drawings inwhich: V

Fig. 1 is an elevation of the bending machine. Fig. 2 is a plan view ofFig. 1.

Fig. 3 is an end view of Fig.2.

can be used with the machine, while 7 Figs. 5 and 6 show a form ofbending arm" which can be used, in'place' of that shown. on the machine,when an ordinary-detachable shield is used.

The machine is provided with a curved former l which has thecross-sectionindicated in Fig. 1 and also shown in end view in Fig. 3and consisting of a semicircular web portion l and side Wings 2 whichare slightly splayed outwardly so that the groove in' the former tapersoutwardly, this former being preferably constructed from a flat stripwhich is first bent transversely to the required cross-section (i. e. asemi-circular web and two splayed side .wings) and this strip is thenbent round intoquadrant form to become the curved and grooved former aswill be clear from Fig. 2. To provide a support for the former one endof this quadrantmerges' into a straight tube 3 whilethe other end of thequadrant is welded to a cross-tube 4 which has its other end welded tothe tube 3at right angles thereto.

Above the former I, but spaced therefrom, is positioned another former 5of smaller size'radius and suitable for tubes of smaller. diameter andthis smaller former may be constructed similarly to the large former Ifrom a strip bent to have a requisite cross-section'and then curved intoquadrant form, its ends being welded to the supporting tubes 3 and 4,'orthe support for this former 5 may be a fiat web 6 which may be formed bypressing in one piece with the former and when the web is provided, asinthe construction shown, the small former 5 is secured to the larger oneby means of extensionsor'brackets l and 8 which are welded to' theexterior oftube 3 and the exterior of tube 4 respectively. Either of thesheet metal formers and their supports may be constructed as unitsseparate from a bending machine so that'they can be sub stituted forother formers, and the'supports can be adapted or modified for use with'other constructions of bending machine than'that illustrated anddescribed.

The cross tube 4 also forms' a support for a pivot pin or bolt 9 onwhichis pivoted a bending lever llL'this lever having two armsw l and I2which extend above and below the larger former land have holes in'theirends through'which the pin 9 passes so that the bending lever- I D canbe swung about its pivot pin 9 'roundthe former "I in the usual manner.Y 'Surrounding the'upper arm H is a slide l3 which has a block portionl4 extending between the two arms H and 12 and to the end of thisslideis attached a vertical bracket [5 to which is attached the shieldI6 associated with the .Which it co-acts.

smaller former 5, while to the block I4 is attached the shield I! whichco-operates with the larger former I.

The concave faces of these shields are not of true semi-circularcross-section but are made slightly oval in cross-section so that thecentral part or root of the concave face, indicated at l8 on shield 11,does not come into contact with the wall of the tube (which is indicatedin chaindotted. outline in Fig. 1) and the tube is thus acted on only bythe parts of the grooved faces of the shields near the edges which taperdown to knife-like edges [9 as shown so that each shield can fit withinthe side wings of the former with Furthermore, the shields l6 and I! arearranged so that only parts of their 7 T edges l9 enter the grooves ofthe formers while Fig. 4 illustrates a supporting memberwhich" of thetube at the start of the bend and itisfound that, by slight compressionand settlement of the tube during thebending operation, the forward edgeof the shield comes into contact with the tube. 7

The two shields l6 and I! are so positioned in relation to one anotherthat they both enter their respective formers when the slide "I 3 ispushed along towards the pivot pin 9 and the slidecan be held inposition by a removable pin 20, which is conveniently attached by achain 2| to the bending lever l0, and is passed through holes in thearms II and I2 and in the slide l3 and block M'which are in alignmentwhen the shields are correctly positioned between the wings of theformers as shown. The 'two shields l6 and H are also positioned on theslide I3 so that the bending force acts between 10 to 25 but preferablyapproximately 15 beyond; a radial line passing through the bendingpoint, but if desired the bending lever I0 can itself be cranked to therequired extent so that the shields are then positioned at right anglesto the cranked part of the bending arm.

There is also provided for each former a stop or abutment against whichthe end of the pipe being bent, or the length of pipe preceding thebending point can bear while the bending operation is in progress, andthese stops are formed by an arm 22 projecting from a ring'23 whichsurrounds the tube 3 and is secured thereto by a screw 24 which projectsthrough a slot 24' in the ring 23 to enable the arm 22 to adjust itself,while it is always kept in a convenient position for the insertion orrelease of the tube. The free end of the arm 22 is bent over as shown at25 in Fig. 3 so that the bent end can fit round the part of the pipewhich projects from the larger former "I while the arm 22 also hassecured to it a curved bracket 26 which similarly acts as a stop or support for pipes bent in the smaller former 5.

. The projecting part of the tube 3 can be gripped in a vise or securedto any other suitable support and the hollow interior of the tube formsa socket for the member 21, shown in Fig. 4, which has a reduced end 28which fits within the tube 3, while the other end of this arm isprovided with V-a rubber-foot29. Thisimember -21 can have its reducedend 28 fitted into tube v3 so that it projects in the same direction asthat in which the bending lever isshown in Fig.2 so that the member 21forms an arm against which theoperator "tube is bent by'swinging .thebending lever in 'a vertical plane. The tube 3 is also provided with atransverse hole 30 inline with the 'cross tube 4 so thatthe reduced end28 of the member 21 can be fitted into the'socket so formed, at rightangles to the position previously mentioned, as thebend- *ing operationproceeds.

In carrying outthe bending operation thebending lever 10 is brought into'a position at right .angles to that shown and the .tube is fitted .be-

tween the side wings of one or other of the formers l or 5, the wings ofthe former being sufficiently springy (owing to the factthat theformeris made of sheet or platemetal) to'accommodate tubes of slightlydifferent external diameters, and the end of the tube or the part wherethe bending is to be commenced is supported by the appropriate stop 25or 26. The slide 13 is moved along the bending lever towards the pivot.pin 9 until the shield fitsbetween the wings of the former and the tubeis enclosed between the grooved face of thezformer andflthershield whichcontacts only at its rear end with the'tube, and

the shield is secured in position by passing the pin 20 through theholes in the arms II and I2 of the bending lever and the hole in .theblock I l-which come into alignment.

The member 21 is then fitted into the tube 3 to give a purchase for thebending operation, and the bending lever ID is then pulled round so thatthe shield travels along the surface to the tube with the end of theshield which projects out from between the wings of the former as theleading or advancing end. It is found that with the arrangement andconstruction of shield as above described it is possible to produce aconsiderable bend in a pipe or tube without distortion of or damage tothe tube and, of course, as the shield travels round with the bendinglever there is no need to suspend the bending movement at intervals toreadjust the position of the shield.

After the bending movement has been started the member 21 can betransferred from its original position in which it forms a continuationof tube 3 to a position in the socket 30 at the side of tube 3 in linewith tube 4 so as to enable greater purchase to be obtained.

If desired, the usual separate shield may be used with a former of thekind above described and in this case the slide l3 and the shields I6and I! carried by the bending lever itself are dispensed with and thelever is of the form shown in Figs. and 6. In this case the arms II andI2 carry pins 3| and 32 on which rotate rollers 33 and 34, one or otherof which can bear on the fiat face of a shield located in the well knownmanner between the roller and the pipe which is being bent. The roller33 is positioned so that it acts on the shield which co-acts with thelarger former I while the other roll-er 34 is positioned so that it canbear on the shield used with the smaller former 5.

Although the machine illustrated has two formers of difierent sizes itwill be obvious that the smaller former can be dispensed with, ifnecessary, so that the machine is only suitable .iorlbendingpipes ofabout .onestandard size although,.of course, ialternativ-e sizes .ofseparate ;unit fformers may be provided for :use with the Zsame bendinlever and shieldby arranging that these .other aformers with theirsupports can be substituted by the operator for that already in themachine.

"Furthermore, although the formers shown only extend throughapproximately a quarter of a circle they can obviously be madesemi-circular or.nearly .completely circular to enable semicircular .andcircular bonds to be producedin a pipe ortube with one sweep of thebending lever. 7

By making a former of sheet-metal, and not as .a casting, the wings orflanges can be made so that they spring slightly when the pipe is placedin ith e groove of the former, thereby producing the top and .bottompressure which is always required in bending pipes; and is particularlynecessary when bendingthe light gauge copper tubes used in modern hotandcold water systems, while, owing to the ability of the sheet metalformer to open out slightly, it can accommodate pipes with slightlydifferent external diameters or pipes of a standard bore but made ofdifferent gauge metal and consequently different thicknesses of wall. Aformer of this kind, therefore, makes it unnecessary to use differentformers for slightly difi-erent-sizes and gauges of lighter than thecast formers, which considerably reduces the weight-of the Wholemachine.

Although the former according to the invention has flanges which project-to the full diameter of thetube to be'bent, this is not essential whenbendingthick walled tubes or a tube which has a spring inserted in itwhile it is being bent and the former can therefore be made ofsemicircular shape in section (without the fully projecting flanges)when thick walled tubes only have to be bent.

Also by the use of a shield of the construction above described it isfound that distortion or damage to'the tube is avoided and an operatorcan produce any required degree of bend up to the limit of the formerwithout it being necessary to adjust the guide while the bendingoperation is in progress.

A machine of the construction shown can also be quickly clamped in avice or can be used apart from any rigid foundation on which to securethe former as the bending lever can be swung round towards the arm .21(when fitted into the tube 3) in a similar manner to the use of a pairof shears, or, of course, this member Z'Ican be pressed against theground and the bending carried out in a vertical plane, as abovementioned. o

What I claim as my invention and. desire to secure by Letters Patent is:

1. In a tube bending machine having a radial sweep arm carrying agrooved member bearing on the tube, a bent up sheet metal formercomprising in cross section a semi-circular part and resilient sideflanges projecting to the overall diameter of the largest tube which canbe fitted into the former, the flanges being splayed slightly so thatthe groove in the former, for the reception of the pipe being bent,tapers outwardly to receive diametrically different size tubes.

2. In a pipe bending machine having a radial sweep arm carrying agrooved member bearing on the pipe, at former consisting of a strip ofsheet metal bent transversely to a semi-circular form with projectingresilient side flanges and curved round longitudinally to the necessaryradius, a tube welded to one end of the grooved strip and forming asupport for the bending machine during use, and a second tube weldedtransversely to the first-mentioned tube and to the other end of thestrip and forming a socket for the pivot about which the sweep armswings.

3. In a tube bending machine having a radial sweep arm capable of beingswung round a grooved former to bend the tube, a grooved shield having acylindrical concave face of slightly greater curvature at its centrethan towards its edges, said shield being slidable on said arm until therear edges of the shield enter the groove in the former.

4. A tube bending machine comprising a bent up sheet metal groovedformer, supporting members welded thereto, a radial bending leverpivoted on one of said members and capable of swinging about saidformer, an abutment adjacent one end of the former, and a grooved shieldslidable on the bending lever until one end of the shield enters thegroove in the former, said shield having a concave face of slightlygreater curvature at the centre than towards its edges.

5. A tube bending machine having a plurality of grooved sheet metalformers of difierent sizes, supporting means for said formers, a bendinglever pivoted on said supporting means and capable of a swingingmovement in relation to said formers, straight grooved members slidinglyadjustable on said lever, one member being associated with each former,means for securing said members in adjusted tube bending position withtheir rear edges only in the grooves of the formers,

and abutments for holding the end of a. tube being bent.

6. A pipe bending machine comprising sheet metal formers, a supportingtube welded to said formers, an additional tube welded to said formerstransversely of the first mentioned tube, a radial bending lever pivotedon said additional tube, grooved shields slidable on said lever andmovable round the formers by swinging movement of said lever,means forsecuring the shields in position on the lever, an arm secured on thefirstmentioned tube and carrying abutments for the end of the pipe to bebent, and a supporting leg insertable into either of the tubes.

7. A pipe bending machine comprising sheet metal formers, a supportingmember secured to said formers, an additional supporting memberconnected to said formers transversely of the first mentioned supportingmember, a radial bending lever pivoted on said'additional supportingmember, grooved shields on said lever and movable round the former byswinging movement of said lever, means for securing the shields inposition on the lever, an arm secured on the first mentioned supportingmember and a stop carried by said arm to engage the end of the pipe tobe bent.

8. For use in a tube bending machine having a radial sweep arm carryinga grooved member bearing on a tube, a former constructed with a groovehaving resilient outer walls tosupport the tube, the said resilientwalls of the groove permitting the insertion of diametrically differentsize tubes.

JOHN HENRY HAWES.

